This invention generally relates to a valve assembly for active combustion control and more particularly to a valve assembly for use in a gas turbine device.
Gas turbine engines are well known. One challenge constantly faced in using such machinery is to control the fuel flow rate so that appropriate fuel delivery levels are achieved. There is a need for valve assemblies to meter the fuel flow to achieve the fuel modulation frequency and phase commanded by the control signal input.
A variety of valve arrangements have been proposed, including linear actuators that move responsive to control signals to open or close fuel flow passages to appropriately meter fuel flow. While linear actuators, such as solenoids, are capable of moving at necessary speeds to achieve desired frequencies, they are not without limitations. One difficulty experienced with linear actuators is that the devices tend to require repair or replacement after a large number of repeated cycles.
Other proposed arrangements have included rotary valves with electric motors providing a motive force to rotate the valve components as needed to control fuel flow. A difficulty associated with such arrangements is the inherent inertia and other control factors associated with utilizing an electric motor. Moreover, having to supply electric power to locations within the fuel flow stream introduces the need to adequately seal off the electrical driver components from the combustible fuel. Such seal arrangements are difficult to achieve and introduce further complexities into the system.
There is a need for an improved valve assembly that has the capability of a linear actuator arrangement with the longevity aspects of prior suggested rotary valves but does not introduce the safety or complexity concerns of prior arrangements. This invention provides such a valve arrangement and avoids the shortcomings and drawbacks of prior attempts.
In general terms, this invention is a valve assembly for controlling fuel flow in a gas turbine engine arrangement.
A valve assembly designed according to this invention includes a valve housing. A main fuel flow pathway extends through at least a portion of the valve housing and terminates in a plurality of outlet members that permit the fuel to exit the main passageway. An actuated fuel passageway preferably extends through a portion of the valve housing. The actuated fuel passageway includes a second plurality of outlet members that permit fuel to exit the actuated fuel passageway. A valve member is supported within the actuated fuel passageway to control the amount of fuel delivered through the second plurality of outlet members. A turbine element preferably is supported within the housing so that the turbine element moves responsive to fuel flow through the housing. The turbine element preferably is associated with the valve member in the actuated fuel pathway so that movement of the turbine element causes movement of the valve member, which results in the desired fuel flow control.
In one example, an electronic controller controls the rate of movement of the turbine element. The turbine element is normally moved at a high rate based upon the existing fuel flow through the housing. The controller preferably controls an electronic brake arrangement that selectively slows down the rate of movement of the turbine element to thereby control the movement of the valve member and the eventual fuel flow from the second plurality of outlet members associated with the actuated fuel pathway.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.